"#DEFCAD has gone dark at the request of the Department of Defense Trade Controls. Take it up with the Secretary of State."

The 3-D printed gun, as we've reported, has been successfully test-fired by Texas-based Defense Distributed. The thought of spreading the know-how to have a 3-D printer produce a firearm is unsettling to some, who worry about the technology getting into the wrong hands, but is liberating to others, who say that Americans should be able to build their own handguns that way (provided they can afford an $8,000 3-D printer).

After more than 100,000 downloads of the plans, of course, going "dark" at the request of the government (suspending such downloads) would seem to be closing the virtual barn long after many, many horses have gotten out.